#include <stdio.h>

int main()
{
    int a;
    scanf("%d",&a);

    if ( (0 == a%2 && 2 != a) || 1 == a)
    printf("no\n");
    else
    {
        int b = 2;
    again:
        if (0 != a%b && b < a)
        {
            b++;
            goto again;
        }
        if ( b == a )
        printf("yes\n");
        else
        printf("no\n");
    }

    return 0;
}